When your baby is put to your breast, the suckling sends a message to your brain. This message releases two hormones. One hormone, prolactin*, causes you to make milk. Your bodymakes more milk every time your baby suckles and swallows. This is called “supply and demand”. The more your baby breastfeeds, the more milk you will produce. The other hormone, oxytocin*, causes the milk-ejection or let-down reflex. The let-down reflex happens when the alveoli release milk into the milk ducts. You may or may not feel a tingling sensation when let-down occurs.
Once your mature milk starts to “come in”, usually around days 2–4 after birth, your breasts will get fuller as milk begins to fill the milk ducts. Your breasts may feel slightly uncomfortable. Breastfeeding more often helps to decrease this discomfort. This feeling of uncomfortable fullness is temporary and will subside once your milk production adjusts to your baby’s needs.
